AU2003258674B2

AU2003258674B2 - Ankle-joint endoprosthesis

Info

Publication number: AU2003258674B2
Application number: AU2003258674A
Authority: AU
Inventors: Arnold Keller; Hakon Kofoed; Helmut D. Link
Original assignee: Stryker European Holdings I LLC
Current assignee: Stryker European Holdings I LLC
Priority date: 2003-08-27
Filing date: 2003-08-27
Publication date: 2009-12-10
Anticipated expiration: 2023-08-27
Also published as: CN1819804A; US20070112431A1; DK1658023T3; US20100198355A1; AU2003258674A2; ATE357195T1; EP1658023A1; ES2282738T3; EP1658023B1; KR20100086066A; US20140081413A1; MXPA06002144A; IL173388A0; JP2007534342A; DE50306880D1; AU2003258674A1; BR0318475A; CN1819804B; US9681958B2; US8591595B2

Description

Ankle-joint endoprosthesis To replace the ankle joint, an endoprosthesis is known comprising a component to be connected to the ankle bone, s a component to be connected to the shin bone, and an intermediate part (DE-U-88 12 806, brochure "LINK S.T.A.R. Totale Sprunggelenkprothese [H. Kofoed] from the company Waldemar Link (GmbH & Co.), Hamburg). The ankle bone component and the intermediate part interact via slide 10 surfaces which permit flexion and extension in the sagittal plane. The shin bone component and the intermediate part form interacting slide surfaces which permit a rotation about the vertical axis. They can be of a plane design in order to permit compensating movements is in the AP direction and LM direction. Stabilization is afforded by the natural ligament apparatus. In the known prosthesis, the top and bottom slide surfaces of the intermediate part are oriented parallel to one 20 another in the frontal plane because the prosthetic replacement of the joint is not intended to result in a change in direction. However, it has been found that, after surgery, the collateral and medial ligaments of the joint often have different tensioning, which can cause 25 problems. This may be due to irregularities of the anatomy or to the fact that the operating surgeon has chosen an unfavourable orientation of the resection surface provided on the shin bone for connection to the prosthesis. 30 It would be advantageous if the present invention would avoid or alleviate an imbalance between, on the one hand, the anatomical or surgical circumstances and, on the other hand, the prosthesis. 35 The present invention provides in a first aspect an endoprosthesis in which the intermediate part and/or the 21067571 (GHMatters) 24/11/09 -2 shin bone component are of a wedge-shaped design. If the operating surgeon finds that the ligament tension is different if a normal prosthesis is used, he can compensate for this by using corrective components which 5 have a wedge shape in the frontal plane. The thicker side of the wedge-shaped corrective plate is arranged on that side on which the ligament tension would be inadequate if normal components were used. If he finds that the tibial resection surface is not perpendicular to the tibial 10 direction or if he wishes, for other reasons, that the prosthesis planes do not extend perpendicular with respect to the axis of the tibia, he can also use corrective components whose wedge shape lies in the sagittal plane. If the operating surgeon wishes that the lower slide is surface of the upper component has a defined orientation with respect to the tibial direction or the direction of loading, he will generally use a shin bone component designed as corrective component. If, by contrast, the orientation of the tibial resection surface is correct and 20 the aim is to take account of the anatomy of the foot, he will prefer an intermediate part design as corrective component. The present invention does not relate to the wedge-shaped 2S design of the intermediate part in the frontal plane since this is the subject matter of the earlier, not prior published patent application PCT/EPO2/02573. Determining that the upper component is wedge-shaped does 30 not in practice cause any difficulties since both its top connection surface and also its bottom slide surface are plane or substantially plane. Comparison with the normal intermediate parts is decisive in determining any wedge shape of the intermediate part in the sagittal plane. 35 Moreover, it is not only simple to determine the direction of the approximately plane top slide surface of the intermediate part, but also the overall orientation of the 21067571 (GHMatters) 24/11/09 - 3 bottom slide surface. An intermediate part is wedge shaped, within the meaning of the present invention, in the sagittal plane when it becomes thicker anteriorly or posteriorly compared to the normal intermediate part. 5 A wedge shape in the sagittal plane can, in the context of embodiments of the present invention, be combined with a wedge shape in the frontal plane. However, the wedge shape can occur in the sagittal or frontal plane also io without a wedge shape in the frontal of sagittal plane. The wedge angle is expediently between 10 and 160, preferably between 30 and 80. 15 To ensure that the orientation of the wedge shape of the intermediate part cannot be altered by rotation of the intermediate part about the vertical axis, its orientation is expediently forcibly fixed by way of the ankle bone or the shin bone, by means of the interacting slide surface 20 pairs being designed accordingly in a manner which defines a direction (for example cylindrically). The joint between the ankle bone and the intermediate part is particularly suitable for this purpose. 25 To ensure that the operating surgeon can choose between different wedge angles, he must have access to several different corrective components for each prosthesis. To reduce the costs associated with this, it is expedient to design the corrective components as simply as possible. 30 It may therefore be expedient for them to be made up of an unchanging standard part and of a wedge part. The standard part is provided in only one configuration. Only the wedge parts need to be provided in different variants. This applies in particular if the upper component is used 35 as corrective component and the standard part forms the means necessary for securing to the shin bone. 2106757_1 (GHMatters) 2411/09 -4 The present invention provides in a second aspect an endoprosthesis for replacing an ankle joint, comprising a lower component which is to be connected to the ankle bone and which forms a top slide surface, an upper component 5 which forms a bottom slide surface and which has an upper connection surface for connection to a resection surface of the shin bone, and an intermediate part which has two slide surfaces interacting with the slide surfaces of the upper and lower components, characterized in that the 10 slide surface of the intermediate part interacting with the bottom slide surfaces of the upper component as well as the bottom slide surface of the upper component are planar or substantially planar, further characterized in that the upper component is wedge-shaped in frontal and/or 15 sagittal section between its bottom slide surface and its top connection surface and/or the intermediate part is wedge-shaped in sagittal section between its slide surfaces. 20 The present invention provides in a third aspect a system of endoprostheses for replacing the ankle joint, comprising a lower component which is to be connected to the ankle bone and which forms a top slide surface, an upper component which forms a bottom slide surface and 25 which has a connection surface of the shin bone, and an intermediate part which has two slide surfaces interacting with the slide surfaces of the upper and lower components, the system including universal upper components and intermediate parts whose top face and bottom face have a 30 substantially parallel overall course, characterized in that the slide surface of the intermediate part, interacting with the bottom slide surface of the upper component as well as the bottom slide surface of the upper component are planar or substantially planer, further 35 characterized in that it includes corrective components which can be used in exchange for the universal upper components and which are wedge-shaped in the sagittal 21067571 (GHMatters) 24/11/09 - 5 plane and/pr frontal plane between their top and bottom faces and/or corrective intermediate parts which can be used in exchange for the universal intermediate parts and which, between their top face and the overall course of 5 the bottom face, are wedge-shaped in the sagittal plane compared to the universal intermediate parts. The invention is explained in greater detail below with reference to the drawing which depicts advantageous 10 illustrative embodiments and in which: Fig. 1 shows a sagittal section through a joint fitted with the prosthesis, 15 Fig. 2 shows the prosthesis in a perspective view and opened out, Fig. 3 shows a perspective view of the arrangement of the implanted upper and lower prosthesis 20 components before the intermediate part is inserted. Fig. 4 shows a frontal section through an upper corrective component, 25 Fig. 5 shows a sagittal section through an upper corrective component, Fig. 6 shows a sagittal section through a corrective 30 intermediate part, and Fig. 7 shows an upper corrective component which is designed in two parts. 35 The prosthesis comprising the upper component 3, the lower component 4 and the intermediate part 5 is to be arranged between the shin bone 1 and the ankle bone 2. The upper 2106757_1 (GHMatters) 24/11/09 - 6 component 3 has a plate-shaped part 6 whose bottom face 7 forms a plane slide surface. Projections 8 are used for securing it in corresponding resection recesses 9 in the shin bone 1. 5 The lower component 4 forms a convexly curved slide surface 10 which can be designed cylindrically or conically. It carries a rib 11 which lies in the direction of the relative movement of the intermediate 10 part during flexion and extension movement. The lower component additionally has lateral facets 12 for interaction with corresponding slide surfaces of the shin bone 1 and of the calf bone 13. 15 The intermediate part 5 has a plane top face 15 matching the slide surface 7, and a bottom slide surface 16 which is designed to complement the slide surface 10 of the lower component 4. It includes a groove 17 for receiving the rib 11. In this way, the intermediate part 5 is 20 guided laterally in relation to the lower component 4. It is allowed only flexion and extension movements. The upper and lower components 3 and 4 are expediently made of metal, and the intermediate part 5 of a plastic 25 that promotes sliding, for example polyethylene. However, other materials with sufficient strength and slidability can also be used, for example ceramic. On account of the complementary shape of the slide 30 surfaces 10 and 16, and by the rib 11 interacting with the groove 17, the intermediate part 5 is nonrotatable about the vertical axis in relation to the ankle-joint component 4. Its orientation is thus fixed by that of the lower component. While the embodiment shown completely rules 35 out rotation movements of this kind between the lower component and the intermediate part about the vertical axis, configurations are also conceivable in which these 21067571 (GHMatters) 24111/09 -7 are permitted within predetermined limits or are merely inhibited by the design of the slide surfaces or are not ruled out. 5 The above explanation with reference to Figures 1 through 3 applies to both to designs with normal components and also to designs with corrective components. Figures 4 through 6 show examples of corrective 10 components. Fig. 4 shows a frontal view of an upper component 3 designed as corrective component. Near the edge 20 appearing on the left in the drawing, it is thicker than at the opposite edge. The component is designed symmetrically in relation to its frontal i5 midplane, such that the thickened side 20 may lie on the lateral side or medial side of the joint, depending on the choice made by the operating surgeon. Fig. 5 shows a sagittal section through the upper 20 component 3. It is thickened in a wedge shape at the end 21 appearing on the left in the drawing. The top face of this component is symmetrical in relation to the frontal plane. Therefore, the thickened end can be arranged anteriorly or posteriorly in the joint, depending on the 25 choice made by the operating surgeon. The wedge angle 22 between the top securing surface 23 and the lower slide surface 7 is of the order of magnitude of 50 in both examples. 30 Fig. 6 shows a sagittal section through a "corrective" intermediate part 5. Its bottom face 16, designed as slide surface, has an overall orientation extending approximately parallel to the auxiliary line 24 which has been drawn in order to illustrate the wedge angle 19 near 35 the top slide surface 15. In an alternative variation of a "normal" or "universal" (non-corrective) intermediate part, line 24 would extend parallel to the top slide 2106757_1 (GHMatters) 24/11/09 -8 surface 15 (the angle 19 would be 00). The critical factor in determining a wedge shape of the intermediate part is always the comparison with the normal components of the prosthetic system. 5 It is not necessary for a correction to be restricted in each case to just one component. Instead, corrective components can be used both for the upper component and also for the intermediate part. This possibility is shown 10 in Fig. 1. As soon as the operating surgeon has implanted the lower component 4, he can use suitable instruments to determined whether, when the collateral ligaments are tensioned, the 15 resection surface 25 of the shin bone has a normal extension relative to the lower component 4 or whether a correction is necessary. In the latter case, he decides whether a corrective component needs to be selected for the upper component or the intermediate part or for both 20 and he decides how pronounced the respective wedge shape needs to be and in what direction it should lie. A corresponding measurement is also still possible when the upper component 3 has been fitted. Thereafter, it is possible to decide whether a corrective component is to be 25 used as intermediate part. Fig. 7 illustrates the composition of the upper component 3 made up of a standard part 25 and a wedge part 26. Since the standard part 25 forms the securing members 8, 30 the wedge part 26, of which several examples with varying wedge angles are made available, can be made correspondingly simpler. The two parts can be connected to one another in any desired and known manner. For example, they can be screwed together. They can also be 35 provided with complementary projections and recesses engaging in one another, making it possible to join the two parts together without any great effort. 2106757_1 (GHMatters) 24111/09 - 9 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any s other country. 21067571 (GHMatters) 24/11/09

Claims

1. An endoprosthesis for replacing an ankle joint, comprising a lower component which is to be connected 5 to the ankle bone and which forms a top slide surface, an upper component which forms a bottom slide surface and which has an upper connection surface for connection to a resection surface, of the shin bone, and an intermediate part which has two io slide surfaces interacting with the slide surfaces of the upper and lower components, characterized in that the slide surface of the intermediate part, interacting with the bottom slide surface of the upper component, as well as the bottom slide surface 15 of the upper component are planar or substantially planar, further characterized in that the upper component is wedge-shaped in frontal and/or sagittal section between its bottom slide surface and its top connection surface and/or the intermediate part is 20 wedge-shaped in sagittal section between its slide surfaces.

2. The endoprosthesis as claimed in claim 1, characterized in that the interacting slide surfaces on the lower component and the intermediate part 25 interact substantially nonrotatably with respect to the vertical axis.

3. The endoprosthesis as claimed in claim 1, characterized in that the interacting slide surfaces on the upper component and the intermediate part 30 interact rotatably with respect to the vertical axis.

4. The endoprosthesis as claimed in one of claims 1 through 3, characterized in that the wedge angle is between 10 and 160.

5. The endoprosthesis as claimed in any one of claims 1 2106757_1 (GHMatters) 24/11/09 - 11 through 4, characterized in that the wedge-shaped component is made up of a wedge part, available with a varying wedge angle, and of a universal part.

6. A system of endoprostheses for replacing the ankle 5 joint, comprising a lower component which is to be connected to the ankle bone and which forms a top slide surface, an upper component which forms a bottom slide surface and which has a connection surface of the shin bone, and an intermediate part 10 which has two slide surfaces interacting with the slide surfaces of the upper and lower components, the system including universal upper components and intermediate parts whose top face and bottom face have a substantially parallel overall course, is characterized in that the slide surface of the intermediate part, interacting with the bottom slide surface of the upper component, as well as the bottom slide surface of the upper component are planar or substantially planer, further characterized in that 20 it includes corrective components which can be used in exchange for the universal upper components and which are wedge-shaped in the sagittal plane and/or frontal plane between their top and bottom faces and/or corrective intermediate parts which can be 25 used in exchange for the universal intermediate parts and which, between their top face and the overall course of the bottom face, are wedge-shaped in the sagittal plane compared to the universal intermediate parts. 30

7. An endoprosthesis substantially as herein described with reference to the drawings.

8. A system substantially as herein described with reference to the drawings. 2106757_1 (GHMatters) 24/11109